HHV-8-associated Kaposi sarcoma in a child with IFNgammaR1 deficiency

Classic Kaposi sarcoma in 3 unrelated Turkish children born to consanguineous kindreds

Infection by human herpesvirus 8 (HHV-8) in childhood is common in the Mediterranean basin; however, classic Kaposi sarcoma (KS) is exceedingly rare in children not infected with HIV and not receiving immunosuppression, with only 30 cases having been reported since 1960. We recently reported 2 children with autosomal and X-linked recessive primary immunodeficiencies underlying KS in a context of multiple clinical manifestations. These reports suggested that classic KS in otherwise healthy children might also result from inborn errors of immunity more specific to HHV-8. In this article, we describe 3 unrelated Turkish children with classic KS born to first-cousin parents. The first patient, a girl, developed KS at 2 years of age with disseminated cutaneous and mucosal lesions. The clinical course progressed rapidly, and the patient died within 3 months despite treatment with vincristine. The other 2 children developed a milder form of KS at the age of 9 years, with multiple cutaneous lesions. A boy treated with interferon alpha therapy for 12 months is now in full remission at the age of 14, 2 years after treatment. The second girl is currently stabilized with etoposide, which was begun 4 months ago. None of the 3 children had any relevant familial history or other clinical features. The occurrence of classic KS in 3 unrelated Turkish children, each born to consanguineous parents, strongly suggests that autosomal recessive predisposition may drive the rare occurrence of HHV-8-associated classic KS in children.

Paternal uniparental isodisomy of chromosome 6 causing a complex syndrome including complete IFN-gamma receptor 1 deficiency

Mendelian susceptibility to mycobacterial disease (MSMD) is a rare primary immunodeficiency associated with clinical disease caused by weakly virulent mycobacterial species. Interferon gamma receptor 1 (IFN-gammaR1) deficiency is a genetic etiology of MSMD. We describe the clinical and genetic features of a 7-year-old Italian boy suffering from MSMD associated with a complex phenotype, including neonatal hyperglycemia, neuromuscular disease, and dysmorphic features. The child also developed necrotizing pneumonia caused by Rhodococcus equi. The child is homozygous for a nonsense mutation in exon 3 of IFNGR1 as a result of paternal uniparental disomy (UPD) of the entire chromosome 6. This is the first reported case of uniparental disomy resulting in a complex phenotype including MSMD.

Autosomal dominant and sporadic monocytopenia with susceptibility to mycobacteria, fungi, papillomaviruses, and myelodysplasia

We identified 18 patients with the distinct clinical phenotype of susceptibility to disseminated nontuberculous mycobacterial infections, viral infections, especially with human papillomaviruses, and fungal infections, primarily histoplasmosis, and molds. This syndrome typically had its onset in adulthood (age range, 7-60 years; mean, 31.1 years; median, 32 years) and was characterized by profound circulating monocytopenia (mean, 13.3 cells/microL; median, 14.5 cells/microL), B lymphocytopenia (mean, 9.4 cells/microL; median, 4 cells/microL), and NK lymphocytopenia (mean, 16 cells/microL; median, 5.5 cells/microL). T lymphocytes were variably affected. Despite these peripheral cytopenias, all patients had macrophages and plasma cells at sites of inflammation and normal immunoglobulin levels. Ten of these patients developed 1 or more of the following malignancies: 9 myelodysplasia/leukemia, 1 vulvar carcinoma and metastatic melanoma, 1 cervical carcinoma, 1 Bowen disease of the vulva, and 1 multiple Epstein-Barr virus(+) leiomyosarcoma. Five patients developed pulmonary alveolar proteinosis without mutations in the granulocyte-macrophage colony-stimulating factor receptor or anti-granulocyte-macrophage colony-stimulating factor autoantibodies. Among these 18 patients, 5 families had 2 generations affected, suggesting autosomal dominant transmission as well as sporadic cases. This novel clinical syndrome links susceptibility to mycobacterial, viral, and fungal infections with malignancy and can be transmitted in an autosomal dominant pattern.

Genetic deficiencies of innate immune signalling in human infectious disease

The type-1 cytokine (interleukin 12, interleukin 23, interferon gamma, interleukin 17) signalling pathway is triggered during infection by activation of phagocyte-expressed pattern-recognition receptors that recognise specific pathogen-associated molecular patterns. Triggering of this pathway results, among other things, in activation of microbicidal mechanisms in phagocytic cells. Individuals with a deficiency in one of the proteins in the pathway are unusually susceptible to otherwise poorly pathogenic, mostly environmental, mycobacteria and salmonellae. Individuals with deficiencies in other innate immune signalling proteins show unusual susceptibility to pathogens other than mycobacteria or salmonellae. We discuss recent insights into key molecules involved in type-1 cytokine signalling pathways and provide an update on the molecular genetic defects underlying mendelian susceptibility to mycobacterial disease. We also discuss deficiencies in the innate immune signalling proteins that lead to susceptibility to other pathogens. Knowledge of innate immune signalling has allowed the identification of defects in such patients. However, some patients have enhanced susceptibility to pathogens even though no mutations have been found in the candidate genes identified thus far. Whereas a few patients might have autoantibodies against type-1 cytokines, others might harbour mutations in new genes and pathways that still need to be identified.

Kaposi's sarcoma in the pediatric population: the critical need for a tissue diagnosis

Kaposi's sarcoma (KS) is a low-grade vascular neoplasm mediated by the human herpesvirus-8. Only 1 clinical subtype, the endemic/African subtype, commonly affects the pediatric population. Although adults with KS often present with cutaneous findings and generalized lymphadenopathy, African children are more likely to present without classic skin findings. Definitive diagnosis requires histologic examination from tissue biopsy; however, as pathology resources are scarce in many developing African countries where KS is prominent, appropriate diagnosis and treatment of the condition are challenging. We report the case of a Malawian child who presented with generalized lymphadenopathy and was presumptively treated for lymphoma, with clinical worsening of his lesions. A diagnosis of KS was made after excisional biopsy of a superficial lymph node, with the initiation of appropriate therapy. The literature regarding pediatric KS is reviewed and recommendations are offered to allow accurate and timely diagnosis of the condition.

Inborn errors of interferon (IFN)-mediated immunity in humans: insights into the respective roles of IFN-alpha/beta, IFN-gamma, and IFN-lambda in host defense

Interferon (IFN) was originally identified as a substance 'interfering' with viral replication in vitro. The first IFNs to be identified were classified as type I IFNs (IFN-alpha/beta and related molecules), two other types have since been identified: type II IFN (IFN-gamma) and type III IFNs (IFN-lambda). Each IFN binds to one of three type-specific receptors. In the mouse model of experimental infections in vivo, IFN-alpha/beta are essential for immunity to most viruses tested, whereas IFN-gamma is important for immunity to a smaller number of viruses, together with bacteria, fungi, and parasites, consistent with IFN-gamma acting as the 'macrophage activating factor.' The precise role of IFN-lambda remains unclear. In recent years, inborn errors affecting the production of, or the response to, IFNs have been reported in human patients, shedding light onto the function of IFNs in natura. Disorders of IFN-gamma production, caused by IL12B, IL12RB1, and specific NEMO mutations, or of IFN-gamma responses, caused by IFNGR1, IFNGR2, and dominant STAT1 mutations, confer predisposition to mycobacterial disease in patients resistant to most viruses. By contrast, disorders of IFN-alpha/beta and IFN-lambda production, caused by UNC93B1 and TLR3 mutations, confer predisposition to herpes simplex encephalitis (HSE) in otherwise healthy patients. Consistently, patients with impaired responses to IFN-alpha/beta, IFN-gamma, and presumably IFN-lambda (carrying recessive mutations in STAT1), or with impaired responses to IFN-alpha/beta and impaired IFN-gamma production (carrying mutations in TYK2), or with impaired production of IFN-alpha/beta, IFN-gamma, and IFN-lambda (carrying specific mutations in NEMO), are vulnerable to mycobacterial and viral infections, including HSE. These experiments of nature suggest that the three types of IFNs play at least two different roles in host defense. IFN-gamma is essential for anti-mycobacterial immunity, whereas IFN-alpha/beta and IFN-lambda are essential for anti-viral immunity. Future studies in humans aim to define the specific roles of IFN-alpha/beta and IFN-lambda types and individual molecules in host defense in natura.

The genetic heterogeneity of mendelian susceptibility to mycobacterial diseases

Primary immunodeficiencies (PIDs) were long thought to be exclusively recessive traits -- autosomal recessive (AR) in most cases, with a few X-linked recessive (XR) diseases. In recent years, autosomal dominant (AD), mitochondrial, polygenic, and even somatic PIDs have been described. However, AR remains the most frequent inheritance pattern among recently described PIDs. Some PIDs have been shown to be genetically heterogeneous. Mendelian susceptibility to mycobacterial diseases (MSMD) displays a high level of genetic heterogeneity. There are 6 MSMD-causing genes, including 1 X-linked gene (nuclear factor-kappaB-essential modulator [NEMO]) and 5 autosomal genes (IFN-gamma receptor 1 [IFNGR1], IFN-gamma receptor 2 [IFNGR2], signal transducer and activator of transcription 1 [STAT1], IL-12 p40 subunit [IL12P40], and IL-12 receptor beta-subunit [IL12RB1]). The X-linked trait is XR; STAT1 deficiency is AD; the IFNGR2, IL12P40 subunit, and IL12RB1 deficiencies are AR; and IFNGR1 deficiency may be AD or AR. Two of the AR traits (IFNGR1, IFNGR2) may be subdivided into complete and partial deficiencies, and 3 AR complete deficiencies (IFNGR1, IFNGR2, IL12RB1) may be subdivided into disorders with and without cell surface expression. Finally, there are 2 types of AD STAT1 deficiency, depending on whether the mutation impairs phosphorylation or DNA binding. Thirteen genetic disorders conferring MSMD have been described, involving 1 XR, 3 AD (2 genes), and 9 AR traits (4 genes). However, no genetic etiology has yet been identified for about half of all patients with MSMD. We expect to identify new XR and AD causes of MSMD, but new AR etiologies of MSMD are also likely to be discovered. The investigation of children from areas in which consanguineous marriages are common will probably facilitate the description of many more AR traits.

From infectious diseases to primary immunodeficiencies

The field of primary immunodeficiencies has expanded, thanks to the exploration of novel clinical phenotypes and their connection with morbid genotypes, and the subsequent exploration of new patients who have known primary immunodeficiency-defining clinical phenotypes and their connection with novel morbid genotypes. This two-way process is becoming increasingly active, particularly for patients who have infectious diseases in whom the underlying immunologic and genetic causes remain mostly unexplained. The authors review how the exploration of children who have clinical infectious diseases caused by mycobacteria, pneumococcus, and herpes simplex virus recently led to the description of three new groups of primary immunodeficiencies. These three examples justify the continuation of the genetic exploration of novel infectious phenotypes and novel patients who have infections. This challenging process will eventually reap its rewards, to the benefit of patients and their families.

Cutaneous and lymphadenopathic Kaposi's sarcoma: a case report and review of literature

Kaposi's sarcoma (KS) of childhood is an extremely rare and unexplained disease. It is usually associated with immunosuppression and human herpes virus 8 (HHV-8) infection. It can involve skin, mucous membranes, lymph nodes and viscera. This investigation describes a case of a 3-year-old boy with cutaneous and lymphangiopathic KS. Initially, the patient presented with cutaneous lesions of KS behind the right ear. Two months later, the disease disseminated not only cutaneously but also to the cervical, axillary and inguinal lymph nodes. Immunological evaluation showed severe lymphocytopenia but without evidence of human immunodeficiency virus infection. The vascular nature of the lesion was supported by positive staining for CD31 and CD34. This study examines the clinicopathologic features of KS in children and summarizes the relevant literature.

Two patients with complete defects in interferon gamma receptor-dependent signaling

Unusual susceptibility to mycobacterial infections can be caused by deleterious mutations in genes that encode the interferon-gamma receptor 1 chain. Such mutations hamper the activation of macrophages by a type 1 immune response and result in enhanced survival of intracellular pathogens. We here report two patients with unusual mycobacterial infections, both diagnosed with homozygous deleterious interferon-gamma receptor 1 gene mutations. Patient 1 became ill after Bacillus Calmette-Guérin vaccination at the age of 9 months and died at the age of 18 months. She carried a homozygous C71Y mutation in the extracellular part of the mature interferon-gamma receptor 1 protein, resulting in the lack of detectable protein expression and absence of interferon-gamma dependent signaling. Patient 2 became ill at the age of 3 years, is still alive at 19 years of age, and has suffered from five successive infection episodes with atypical mycobacteria. A homozygous splice-site mutation in intron 3 was identified, resulting in the deletion of exon 3 at the mRNA level and consequently a truncated interferon-gamma receptor 1 protein with absence of the transmembrane domain. Protein expression and interferon-gamma dependent signaling were not detectable.

Host genetics of mycobacterial diseases in mice and men: forward genetic studies of BCG-osis and tuberculosis

In humans, genetic factors have long been suspected to contribute to the onset and outcome of tuberculosis. Such effects are difficult to identify owing to their complex inheritance, and to the confounding impact of environmental factors, notably pathogen-associated virulence determinants. Recently, forward genetic approaches in mouse models and in human populations have been used to elucidate a molecular basis for predisposition to mycobacterial diseases. The genetic dissection of host predisposition to infection with Mycobacterium bovis BCG and M. tuberculosis will help to define the key molecules involved in host antituberculous immunity and should provide new insights into this important infectious disease.

Virale Infektionen

Adenoviren verursachen im Kindesalter Krankheiten der Atemwege und des Darms, aber auch Krankheiten der Harnwege, der Lymphorgane und kardiologische und neurologische Manifestationen werden beobachtet. Einige typische Krankheitsbilder können klinisch diagnostiziert werden.

Inborn errors of IL-12/23- and IFN-γ-mediated immunity: molecular, cellular, and clinical features

Mendelian susceptibility to mycobacterial diseases confers predisposition to clinical disease caused by weakly virulent mycobacterial species in otherwise healthy individuals. Since 1996, disease-causing mutations have been found in five autosomal genes (IFNGR1, IFNGR2, STAT1, IL12B, IL12BR1) and one X-linked gene (NEMO). These genes display a high degree of allelic heterogeneity, defining at least 13 disorders. Although genetically different, these conditions are immunologically related, as all result in impaired IL-12/23-IFN-gamma-mediated immunity. These disorders were initially thought to be rare, but have now been diagnosed in over 220 patients from over 43 countries worldwide. We review here the molecular, cellular, and clinical features of patients with inborn errors of the IL-12/23-IFN-gamma circuit.

Kaposi's sarcoma in a child with Wiskott-Aldrich syndrome

INTRODUCTION

Kaposi's sarcoma (KS) is rare in childhood. It may be favored by acquired immune deficiencies, but the predisposing factors to KS in other children are unclear.

DISCUSSION

KS has been reported in only two children and one adult with primary immunodeficiency. We report here a Tunisian child with a Wiskott-Aldrich syndrome who developed KS at the age of 14 months.

CONCLUSION

This observation expands the spectrum of primary immunodeficiencies associated with KS in childhood.

Syndrome de susceptibilite mendélienne aux infections mycobacteriennes : défauts de l’axe Interleukine-12 - Interféron

INTRODUCTION

Environmental non tuberculous mycobacteria and Bacillus Calmette-Guerin vaccines are weakly virulent mycobacteria. Nevertheless they may cause severe diseases in otherwise healthy children with no overt immunodeficiency. Parental consanguinity and familial forms are frequently observed among these patients, therefore this syndrome was named "Mendelian Susceptibility to Mycobacterial Disease".

STATE OF THE ART

In the last nine years, fife genes have been found to be mutated in patients with this syndrome: IFNGR1, IFNGR2, STAT1, IL12B, IL12RB1. Allelic heterogeneity accounts for ten distinct genetic disorders. Clinical phenotype differs between patients. The spectrum of disease extends from early-onset overwhelming mycobacterial infection to adult-onset localized disease and tuberculosis. Impaired IFN-gamma-mediated immunity is the common mechanism of the disease, outlining its major role in mycobacterial immunity.

PERSPECTIVES AND CONCLUSIONS

Better understanding of these disorders reveals an expanding clinical phenotype which justifies studying adult patients with pulmonary non tuberculous mycobacterial infection without known risk factors, severe BCGitis and recurrent tuberculosis. Molecular diagnosis makes it possible to introduce a specific regimen based on physiopathology.

Epidemiological and clinical characteristics of classic Kaposi's sarcoma in Peru

BACKGROUND

Classic Kaposi sarcoma (KS) occurs predominantly among the elderly, with predominance among Jews, Italians, and Greeks. Classic KS has been seen relatively frequently in Peru.

OBJECTIVE

Our purpose was to outline the epidemiological and clinical profile of classic KS in Peru.

METHODS

Epidemiological and clinical features of all classic KS cases diagnosed between 1969 and 2003 at Hospital Nacional Cayetano Heredia (HNCH) and between 1946 and 2004 at Instituto Nacional de Enfermedades Neoplasicas (INEN) were reviewed and studied retrospectively.

RESULTS

An overall incidence of 2.54 per 10,000 attended patients was obtained at the INEN during the 48-year period (mean, 2.39; standard deviation: 1.99; 95% confidence interval, 2.92-1.86). Twenty-one cases were discovered at HNCH and 106 cases at INEN. A male/female ratio of 2.62:1 was found. Mean age at diagnosis was 68.5 years. Lower limbs were involved in 109 patients (85.8%); the trunk was involved in 11 patients (8.6%). Nodules were the most common type of lesion (85.8%); less commonly found were plaques (27.5%), macules (12.5%), papules (12.5%), and ulcers (8.6%). Sixty-two patients had no symptoms (48.8%). Pain was the most common symptom (26.7%), followed by edema (21.2%), bleeding (14.9%), and pruritus (3.9%). A second primary malignancy was found in 11 patients (8.6%).

LIMITATIONS

These results were obtained from patients with classic KS in Peru and may not be applicable to other populations.

CONCLUSION

Classic KS is quite common in Peru with sporadic cases found throughout the country and some clustering in the coastal region. Classic KS in Peru has a clinical presentation that is very similar, but not identical, to the classic KS described in the Mediterranean region, exhibiting some special clinical and epidemiological characteristics with a nodular, nonsymmetric presentation that usually affects the lower extremities.

Génétique et immunité de la tuberculose

Tuberculosis, caused by Mycobacterium tuberculosis, is the most common mycobacterial disease in the world and remains a leading public health problem. Numerous other mycobacterial species are present in the environment and are most often termed atypical or nontuberculous mycobacteria. Like the attenuated vaccine Bacille Calmette-Guérin (BCG) they are generally poorly virulent, even so they can be at the origin of severe infections if the host immune response is impaired. It has been clearly demonstrated that the intrinsic virulence of a mycobacterial species is not the only factor determining disease severity, which is illustrated by the observation that the majority of individuals infected with M. tuberculosis do not develop clinical disease. Numerous arguments suggest that disease severity depends largely on susceptibility/resistance determined by the host genetic make up. In the following review we will discuss the studies on the genes implicated in complex predisposition to tuberculosis and Mendelian predisposition to disease caused by less virulent mycobacteria, proposing a continuous spectrum between those two types of predisposition.

The role of IL-12, IL-23 and IFN-gamma in immunity to viruses

IL-12, IL-23 and IFN-γ form a loop and have been thought to play a crucial role against infectious viruses, which are the prototype of “intracellular” pathogens. In the last 10 years, the generation of knock-out (KO) mice for genes that control IL-12/IL-23-dependent IFN-γ-dependent mediated immunity (STAT1, IFN-γR1, IFNγR2, IL-12p40 and IL-12Rβ1) and the identification of patients with spontaneous germline mutations in these genes has led to a re-examination of the role of these cytokines in anti-viral immunity. We here review viral infections in mice and humans with genetic defects in the IL-12/IL-23-IFN-γ axis. A comparison of the phenotypes observed in KO mice and deficient patients suggests that the human IL-12/IL-23-IFN-γ axis plays a redundant role in immunity to most viruses, whereas its mouse counterparts play a more important role against several viruses.

Clinical features of dominant and recessive interferon gamma receptor 1 deficiencies

BACKGROUND

Interferon gamma receptor 1 (IFNgammaR1) deficiency is a primary immunodeficiency with allelic dominant and recessive mutations characterised clinically by severe infections with mycobacteria. We aimed to compare the clinical features of recessive and dominant IFNgammaR1 deficiencies.

METHODS

We obtained data from a large cohort of patients worldwide. We assessed these people by medical histories, records, and genetic and immunological studies. Data were abstracted onto a standard form.

FINDINGS

We identified 22 patients with recessive complete IFNgammaR1 deficiency and 38 with dominant partial deficiency. BCG and environmental mycobacteria were the most frequent pathogens. In recessive patients, 17 (77%) had environmental mycobacterial disease and all nine BCG-vaccinated patients had BCG disease. In dominant patients, 30 (79%) had environmental mycobacterial disease and 11 (73%) of 15 BCG-vaccinated patients had BCG disease. Compared with dominant patients, those with recessive deficiency were younger at onset of first environmental mycobacterial disease (mean 3.1 years [SD 2.5] vs 13.4 years [14.3], p=0.001), had more mycobacterial disease episodes (19 vs 8 per 100 person-years of observation, p=0.0001), had more severe mycobacterial disease (mean number of organs infected by Mycobacterium avium complex 4.1 [SD 0.8] vs 2.0 [1.1], p=0.004), had shorter mean disease-free intervals (1.6 years [SD 1.4] vs 7.2 years [7.6], p<0.0001), and lower Kaplan-Meier survival probability (p<0.0001). M avium complex osteomyelitis was more frequent in dominant than in recessive patients (22/28 [79%] vs 1/8 [13%], p=0.002), and this disorder without other organ involvement arose only in dominant patients (9/28 [32%]). Disease caused by rapidly growing mycobacteria was present in more recessive than dominant patients (7/22 [32%] vs 1/38 [3%], p=0.002).

INTERPRETATION

Recessive complete and dominant partial IFNgammaR1 deficiencies have related clinical phenotypes, but are distinguishable by age at onset, dissemination, and clinical course of mycobacterial diseases. A strong correlation exists between IFNGR1 genotype, cellular responsiveness to interferon gamma, and clinical disease features.

Inherited disorders of cytokines

PURPOSE OF REVIEW

Cytokines are soluble mediators involved in the development or function of the immune system. This paper reviews the literature on childhood-onset inherited disorders associated with impaired cytokine-mediated immunity.

RECENT FINDINGS

Cytokine-mediated immunity defects can be classified into seven different groups: defects in the interleukin (IL)-7 receptor (IL7RA), in the common cytokine receptor gamma chain (gammac) of the IL-2, -4, -7, -15, and -21, and in Jak3 (JAK3) downstream of the gamma chain; mutation in the IL-2 receptor alpha (IL-2RA) and defective expression of the IL-2Rbeta chain; mutations in the gene encoding for a chemokine receptor, CXCR4; mutations in five genes involved in the IL-12/23-interferon-gamma axis (IL12B, IL12RB1, IFNGR1, IFNGR2, STAT1); mutations in three genes involved in the nuclear factor-kappaB signaling pathway (IRAK4, NEMO, IkappaBA); mutations in the tumor necrosis factor receptor signaling pathway (TNFRSF1A); and mutations in the transforming growth factor-1 gene (TGFB1).

SUMMARY

Genetic cytokine-mediated immunity defects are associated with a highly heterogeneous group of clinical features, ranging from susceptibility to infections to developmental defects. This heterogeneity highlights the diversity and pleiotropy of cytokines. It is likely that many more cytokine defects and their responsive pathways will be discovered in the coming years, expanding further the heterogeneity associated with this group of childhood-onset illnesses.

Hematopoietic stem cell transplantation for complete IFN-gamma receptor 1 deficiency: a multi-institutional survey

OBJECTIVES

To evaluate the outcome of hematopoietic stem cell transplantation (HSCT) in a series of patients with inherited complete IFN-gamma receptor 1 (IFNgammaR1) deficiency.

STUDY DESIGN

We report 8 patients who received altogether 11 HSCT from family donors, including 10 HLA-identical (5 siblings and 5 relatives) and 1 HLA-haplo-identical donors. Five grafts were T-cell depleted, and conditioning regimens varied in intensity.

RESULTS

Four patients died within 8 months after HSCT. Two of these deaths were due to specific complications related to mycobacterial infection. There was no or very low (2%) donor cell engraftment in 2 survivors. Only 2 patients are in full remission of mycobacterial disease 5 years after HSCT. These are the only patients who received non-T-cell-depleted grafts from an HLA-identical sibling after a fully myeloablative conditioning regimen.

CONCLUSIONS

HSCT can lead to prolonged remission of mycobacterial disease in children with complete IFNgammaR1 deficiency. However, optimal control of mycobacterial infection before HSCT and the use of a non-T-cell-depleted transplant from an HLA-identical sibling after a fully myeloablative conditioning regimen are recommended.